I have a bunch of questions of a B18b with GSR or ITR internals?

1) What are the differences between the ITR and GSR Pistons and rods? I know that the ITR has a higher compression. What is the difference between the rods? Are ones stronger than the others? Both ITR and GSR Pistons and rods should drop right in to the LS block,right?

2) If a GSR head is put on the LS block, is it worth getting rid of the GSR cams for ITR cams or maybe getting some SKunk2 cams?

3) If a GSR head is put on the LS block, you would need the VTEC ECU, right?

Finally..

Money to Performance, is it worth getting the ITR internals or GSR internals?

Thanks